This invention relates generally to row marking apparatus for agricultural implements and particularly relates to an improved row marker for a multi-row planter or cultivator for the accurate positioning of ground working implements relative to crop rows.
In a conventional agricultural tillage apparatus such as a cultivator or planter, a pair of row markers are generally provided. These row markers project laterally from opposite sides of the tractor or frame to which the soil working implements are mounted. Each row marker may be moved between an extended or use position and a retracted storage or road travel position. In the use position, a row marker provides a visible indication for guiding the operator in subsequent passes of the implement over the field being worked. The positioning mark is generally made in the soil by a disc-like member positioned at the distal end of the row marker arm. In general, the markers on opposite sides of the tractor are alternately utilized with the inactive marker in the storage position so as not to contact the soil while the other marker is engaging the soil.
Early row marker systems employed two sets of cables for individually controlling each marker arm. This approach was later replaced with hydraulic control systems in which the tractor's hydraulic system energized a cylinder arrangement for the extension or retraction of the marker arms. The marker arms themselves are generally of a hinged nature having an inner and outer section, with the proximal end of the inner section hinged to the implement-carrying apparatus and its distal end pivotally coupled to the proximal end of the outer section. When the implement is being transported to and from the working area, the hinged marker arm is stored in a flexed position with the various sections generally oriented vertically.
Prior art row marker systems suffer from various operating limitations. One of the primary disadvantages of these systems relates to the transportability and maneuverability of the implement carrying apparatus or tractor, as the case may be. Even in the fully retracted position, these systems generally project laterally outward from the supporting structure, increasing the overall width of the tillage apparatus. In addition, in the retracted position the flexible marker arms extend a considerable height above the tractor and implement carrying structure requiring that the row marker system be removed from the structure to which it is mounted prior to storage unless the storage structure is provided with an over-sized access door. With increasing tillage implement size, marker arm length has correspondingly increased requiring even larger access openings to accommodate current marker arm assemblies.
Another disadvantage of prior art marker arm systems involves the use of complicated arrangements of cables or chains for lowering and raising the marker assemblies. Variations in ground contour and the resulting upward and downward movement of the marker arm assemblies frequently cause the chains or cables to jump from the drive rollers or sprockets with which they are engaged. If the cables or chains are maintained under considerable tension when the marker arm is in the down position so as to avoid this problem, the ability of the marker arm assembly to follow low spots in ground contour by virtue of gravity action is considerably limited.
The increasing size of marker arm assemblies has increased the susceptibility of these systems to damage. For example, impact with a rock of a row marker coupled to a heavier marker arm is more likely to cause damage to the marker itself and/or the arm assembly due to the increased inertia of the entire mechanism. A lighter row marking implement will be more easily deflected by the obstruction and less likely to be damaged thereby. The alternative, of course, is to raise the marker arm prior to impact with an obstruction, but this frequently necessitates raising all of the soil working implements thus interrupting the cultivating process. Even if the position of the row marker is controllable independent of that of the soil working implements, this requires the operator, who already has a number of important functions to perform including that of monitoring the status of the working implements, to be diligent in terms of anticipating impact of the row marker with an obstruction, which in many cases may lie concealed under the surface of the soil. In addition, when the implement carrying assembly is lowered rapidly, the marker arm will also be lowered rapidly and in many cases, for all practical purposes, will fall freely. When working fairly hard soil, if the marker arm falls freely impact between the mark forming means and the ground is considerable. This high impact in some cases may actually result in the bending of the marker arm structure. The thinner, longer marker arm assemblies currently in use are even more susceptible to positioning impact with hard soil.
The present invention is intended to avoid the aforementioned performance limitations of prior art agricultural row markers by providing a row marker system which is more easily and safely transported, provides ground contour following, is highly reliable, and reduces the hazards of an unwieldy, cable - or chain-operated row marker system.